Route profile
DEN→IAD
Flight reliability, delays and best times to fly from Denver to Washington, 1,452 miles.
Right now
Aviation weather is not currently a factor.
Aviation weather is not currently a factor.
Route reliability
July 2023 – July 2026
Better than 56% of comparable major US routes (4,598 compared)
Calculated from 10,253 flights. How this is calculated
DEN → IAD arrives on time 78.7% of the time; the return trip, IAD → DEN, arrives on time 81.5% of the time, a 2.7-point gap between the two directions of the same city pair.
DEN → IAD spends 27.0 minutes on the ground on a 1,452-mile trip: 20.0 minutes from pushback to wheels-up at DEN and 7.0 minutes from touchdown to gate at IAD.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What stands out
On-time performance swings unusually widely by time of day here, wider than 93% of 4,023 comparable routes.
91.2% on time for 5–9 AM departures, against 59.3% for 6–9 PM.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Ranked against every other route with the same kind of figure and at least 4,023 in the comparison.
Why DEN → IAD flights are cancelled
July 2023 – July 2026
DEN → IAD cancelled 99 of 10,253 scheduled flights — about 1 in every 104. The reason filed most often was the airline, 68.7% of the cancellations coded on this route — about 1 in every 151 scheduled flights.
Share of cancellations
Of 99 cancelled departures carrying a reason code.
What each reason means
Crew, maintenance, aircraft cleaning, baggage or fueling: what BTS counts as within the carrier’s own control.
68 cancellations, 68.7% of the total.
Conditions the carrier judged severe enough to stop the flight: a blizzard, a hurricane, a line of thunderstorms.
26 cancellations, 26.3% of the total.
Airport capacity, air traffic control flow programs, heavy traffic and ordinary bad weather. A system decision, not the airline’s.
5 cancellations, 5.1% of the total.
A terminal evacuation, a security breach, screening equipment failure, or screening queues over 29 minutes.
0 cancellations, 0.0% of the total.
Reason codes are the operating airline’s own filing with US DOT, not an independent finding of fault. With only one or two carriers on the route, the split mostly reflects how they file. Ordinary bad weather is filed under air traffic, so weather’s full share is larger than its bar.
99 coded cancellations were recorded on DEN → IAD; the section appears from 50.
When it goes wrong
July 2023 – July 2026
41 min late
against a median of 5 min early
Percentiles over 10,253 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at IAD after arriving from DEN.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 38% | Likely to miss |
| 45 min | 20% | High risk |
| 60 min | 13% | Some risk |
| 90 min | 6.7% | Some risk |
| 120 min | 4.3% | Low risk |
This is one leg of a connection. Gate changes and the next flight's own schedule matter too. And a connection can fail before delay is even the question — this route cancels 0.97% of the time and diverts 0.16% of the time, which a late arrival never shows up in.
Chance of missing is the share of 10,138 arrivals on this route that landed later than the connection time less 30 minutes to reach the next gate.
The worst tenth of arrivals on this route land at least 41 minutes late (90th-percentile gate arrival delay), over 10,253 operations.
Any other layover length: connection checker.
Best time to fly
DEN → IAD flights departing 5–9 AM arrived on time 91.2% of the time, against 59.3% for 6–9 PM departures, a gap of 31.9 percentage points.
By departure window
By departure hour
- 12 AM to 5 AM: too few flights to score
- 6 AM: 93.1% on time from 813 flights
- 7 AM: 90.7% on time from 562 flights
- 8 AM: 89.7% on time from 887 flights
- 9 AM: 81.2% on time from 448 flights
- 10 AM: 77.7% on time from 1,235 flights
- 11 AM: 77.7% on time from 471 flights
- 12 PM: 76.0% on time from 223 flights
- 1 PM: 79.5% on time from 1,256 flights
- 2 PM: 70.9% on time from 264 flights
- 3 PM: 77.9% on time from 806 flights
- 4 PM: 76.7% on time from 408 flights
- 5 PM: 65.0% on time from 1,172 flights
- 6 PM: 66.8% on time from 450 flights
- 7 PM: 50.3% on time from 333 flights
- 8 PM to 10 PM: too few flights to score
- 11 PM: 86.7% on time from 901 flights
Why DEN → IAD runs late
July 2023 – July 2026
the inbound aircraft was late, so this flight started late
crew, maintenance, boarding and fueling, all within the carrier’s control
airspace and airport capacity, including weather-driven flow control
weather severe enough to stop this flight specifically
screening or terminal security incidents
Share of the delay minutes US DOT attributed to each cause for DEN → IAD. Only delays of 15 minutes or more are attributed.
Late-arriving aircraft is the largest cause on DEN → IAD, at 46.8%: flights here mostly leave late because the plane came in late, and the day shows it: 5–9 AM departures arrived on time 91.2% of the time and 6–9 PM departures 59.3%.
How this route holds up in bad weather
July 2023 – July 2026
Bad weather raises cancellations by a similar amount at both ends of DEN to IAD: 4.0 times the normal rate at DEN and 3.1 times at IAD. Cancelled in bad weather against normal hours: DEN 2.8% against 0.7%, IAD 3.3% against 1.0%. Flights that did leave DEN in bad weather arrived on time 51.5% of the time, against 78.8% in normal hours.
Bad weather and normal hours at the airports
Scheduled departures, July 2023 – July 2026| Departures from | DEN | IAD |
|---|---|---|
| Cancelled in bad weather | 2.8% | 3.3% |
| Cancelled in normal hours | 0.7% | 1.0% |
| Arrived on time, bad weather | 51.5% | 69.1% |
| Arrived on time, normal hours | 78.8% | 82.7% |
| Departures in bad weather | 92,610 | 17,867 |
United Airlines (1.5% cancelled against 3.5% for the other carriers at DEN) and Southwest Airlines (2.4% cancelled against 3.1% for the other carriers at DEN) cancelled fewer departures from DEN in bad weather than the other carriers there did in the same months. None of the route’s other carriers was clearly worse.
This route’s airlines in bad weather at DEN
All departures from DEN| Airline | Bad-weather departures | Cancelled | Other carriers |
|---|---|---|---|
| United Airlines | 30,853 | 1.5%below the others | 3.5% |
| Southwest Airlines | 28,467 | 2.4%below the others | 3.1% |
These are airport figures, not route figures: every scheduled departure from DEN and IAD, to any destination, in hours the weather report called bad. The airline rows count each carrier’s departures from DEN on every route.
Weather source and limits. In full: DEN (airlines), IAD, What Weather Costs Each Airport, Who Cancels More When the Weather Turns, Airports That Change Places When Weather Turns.
Airlines on this route
Carriers with at least 200 flights, by the airline that operated each one.
| Carrier | Flights | On time | Cancelled | Median delay | Severe |
|---|---|---|---|---|---|
| United Airlines | 7,845 | 81.6% | 1.13% | -8 min | 6.7% |
| Southwest Airlines | 2,408 | 69.4% | 0.42% | 3 min | 7.4% |
United Airlines flew 76.5% of the 10,253 flights listed.
United Airlines arrived on time 12.2 percentage points more often than Southwest Airlines on this route.
Flights on this route
Flight numbers with at least 600 operations here and still on the schedule.
UA1101 (8:00 AM) arrived on time 91.0% of the time, 22.0 points more often than UA2408 (6:00 PM) at 69.0%.
Weekly and seasonal patterns
By day of week
Wednesday is historically the most reliable day and Sunday the least, a gap of 5.0 percentage points.
By month
- Jan: 79.9%
- Feb: 82.4%
- Mar: 78.7%
- Apr: 81.9%
- May: 74.2%
- Jun: 73.3%
- Jul: 69.5%
- Aug: 75.2%
- Sep: 80.4%
- Oct: 85.5%
- Nov: 85.5%
- Dec: 84.6%
July is historically the weakest month and October the strongest, a spread of 16.0 percentage points.
Reliability over time
July 2023 – July 2026
- July 2023: 70.5% from 264 flights
- August 2023: 80.0% from 277 flights
- September 2023: 76.7% from 248 flights
- October 2023: 84.3% from 249 flights
- November 2023: 83.3% from 204 flights
- December 2023: 81.2% from 234 flights
- January 2024: 66.1% from 221 flights
- February 2024: 76.5% from 201 flights
- March 2024: 75.4% from 253 flights
- April 2024: 77.8% from 262 flights
- May 2024: 69.8% from 301 flights
- June 2024: 75.3% from 290 flights
- July 2024: 73.8% from 302 flights
- August 2024: 75.1% from 296 flights
- September 2024: 84.8% from 286 flights
- October 2024: 86.9% from 283 flights
- November 2024: 85.5% from 278 flights
- December 2024: 86.8% from 274 flights
- January 2025: 79.8% from 254 flights
- February 2025: 85.2% from 230 flights
- March 2025: 84.9% from 293 flights
- April 2025: 79.1% from 292 flights
- May 2025: 72.3% from 311 flights
- June 2025: 65.9% from 326 flights
- July 2025: 64.3% from 361 flights
- August 2025: 71.3% from 335 flights
- September 2025: 79.1% from 292 flights
- October 2025: 85.2% from 283 flights
- November 2025: 87.2% from 275 flights
- December 2025: 85.2% from 307 flights
- January 2026: 89.2% from 279 flights
- February 2026: 84.4% from 257 flights
- March 2026: 75.5% from 300 flights
- April 2026: 88.3% from 291 flights
- May 2026: 80.4% from 316 flights
- June 2026: 80.2% from 262 flights
- July 2026: 70.5% from 266 flights
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 81.2% against 78.5% in the 12 months before — improving by 2.7 percentage points.
Data and methodology
Calculated by FlyerIntel from 10,253 DEN → IAD flight records from the US DOT Bureau of Transportation Statistics, covering July 2023 – July 2026. Late means 15 or more minutes past scheduled arrival; cancelled and diverted flights are left out of on-time rates.
Full methodology · Data sources · Report a problem
Related research: How Long a Layover Needs to Be · Two Airlines on One Route · Best Time of Day to Fly From Major US Airports
Analysis last recomputed